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Abstract:

A method of manufacturing a light emitting diode, includes a process of
forming an n-type nitride semiconductor layer, a light emitting layer,
and a p-type nitride semiconductor layer on a temporary substrate, a
process of forming a p-type electrode on the p-type nitride semiconductor
layer, a process of forming a conductive substrate on the p-type
electrode, a process of removing the temporary substrate to expose the
n-type nitride semiconductor layer, a process of forming a nanoimprint
resist layer on the n-type nitride semiconductor layer, a process of
pressing the nanoimprint mold on the nanoimprint resist layer to transfer
the nano-pattern onto the nanoimprint resist layer, and a process of
separating the nanoimprint mold from the nanoimprint resist layer having
the nano-pattern and etching a portion of the nanoimprint resist layer
having the nano-pattern to form an n-type electrode.

Claims:

1. A method of manufacturing a nanoimprint mold, the method comprising:
forming a support substrate supporting a nitride semiconductor substrate
on one surface of the nitride semiconductor substrate; forming a
nano-pattern having a pyramid shape on the other surface of the nitride
semiconductor substrate through wet etching in which the nitride
semiconductor substrate comprising the support substrate is immersed into
one etchant selected from a calcium hydroxide solution and a sodium
hydroxide solution to irradiate ultraviolet rays onto the nitride
semiconductor substrate; transferring the pyramid-shaped nano-pattern
formed on the other surface of the nitride semiconductor substrate onto
the nanoimprint mold in an nanoimprinting manner; and separating the
nanoimprint mold, on which the pyramid-shaped nano-pattern is formed,
from the nitride semiconductor substrate.

2. The method of claim 1, wherein the nano-pattern of the nanoimprint
mold is controlled by adjusting at least one of a molarity of the etchant
and a wet etching time.

3. The method of claim 2, wherein the etchant has a molarity of about 1 M
to about 8 M, and the wet etching time ranges from about 1 minute to
about 60 minutes.

4. A method of manufacturing a light emitting diode, the method
comprising: forming an n-type nitride semiconductor layer, a light
emitting layer, and a p-type nitride semiconductor layer on a temporary
substrate; forming a p-type electrode on the p-type nitride semiconductor
layer; forming a conductive substrate on the p-type electrode; removing
the temporary substrate to expose the n-type nitride semiconductor layer;
forming a nanoimprint resist layer on the n-type nitride semiconductor
layer; pressing the nanoimprint mold manufactured by the method of claim
1 on the nanoimprint resist layer to transfer the pyramid-shaped
nano-pattern formed on the nanoimprint mold onto the nanoimprint resist
layer; separating the nanoimprint mold from the nanoimprint resist layer
having the pyramid-shaped nano-pattern; and etching a portion of the
nanoimprint resist layer having the pyramid-shaped nano-pattern to form
an n-type electrode.

5. The method of claim 4, further comprising forming a refractive index
adjustment layer between the n-type nitride semiconductor layer and the
nanoimprint resist layer, wherein the refractive index adjustment layer
has a refractive index less than that of the n-type nitride semiconductor
layer and greater than that of the nanoimprint resist layer.

6. The method of claim 5, wherein the refractive index adjustment layer
is formed by sequentially stacking a first refractive index adjustment
layer and a second refractive index adjustment layer which refract light
emitted from the light emitting layer by refractive indexes different
from each other.

7. The method of claim 6, wherein the first refractive index adjustment
layer is formed on the n-type nitride semiconductor layer and has a
refractive index less than that of the n-type nitride semiconductor
layer, and the second refractive index adjustment layer is formed on the
first refractive index adjustment layer and has a refractive index less
than that of the first refractive index adjustment layer and greater than
that of the nanoimprint resist layer.

10. The method of claim 9, wherein the MgO-based oxide forming the second
refractive index adjustment layer is a multinary-compound formed by
adding the other elements in MgO.

11. The method of claim 4, wherein the n-type electrode is formed by
depositing a conductive material on an etched area after a portion of the
nanoimprint resist layer having the nano-pattern is etched to expose the
n-type nitride semiconductor layer.

12. A light emitting diode manufactured by the method of claim 4.

13. A method of manufacturing a light emitting diode, the method
comprising: forming an n-type nitride semiconductor layer, a light
emitting layer, and a p-type nitride semiconductor layer on a substrate
on which a pattern scattering and reflecting incident light is formed;
mesa-etching portions of the p-type nitride semiconductor layer, the
light emitting layer, and the n-type nitride semiconductor layer to
expose a portion of the n-type nitride semiconductor layer; forming a
transparent electrode on the p-type nitride semiconductor layer; forming
the nanoimprint resist layer on the transparent electrode; pressing the
nanoimprint mold manufactured by the method of claim 1 on the nanoimprint
resist layer to transfer the pyramid-shaped nano-pattern formed on the
nanoimprint mold onto the nanoimprint resist layer; separating the
nanoimprint mold from the nanoimprint resist layer having the
nano-pattern; and etching a portion of the nanoimprint resist layer
having the nano-pattern to form a p-type electrode and form an n-type
electrode on the n-type nitride semiconductor layer.

15. The method of claim 13, wherein the p-type electrode is formed by
depositing a conductive material on an etched area after a portion of the
nanoimprint resist layer having the nano-pattern is etched to expose the
transparent electrode.

16. A light emitting diode manufactured by the method of claim 13.

Description:

CROSS REFERENCE TO PRIOR APPLICATIONS

[0001] This application is a Continuation Application of PCT International
Patent Application No. PCT/KR2011/008158, filed on Oct. 28, 2011, under
35 U.S.C. §120 and §365, which claims priority to Korean Patent
Application No. 10-2010-0139057, filed on Dec. 30, 2010, which are all
hereby incorporated by reference in their entirety.

BACKGROUND

[0002] The present invention relates to a method of manufacturing a
nanoimprint mold, a method of manufacturing a light emitting diode using
the nanoimprint mold manufactured thereby, and the light emitting diode
manufactured thereby.

[0003] Gallium nitride-based (GaN-based) white light emitting diodes
(LEDs) have high energy conversion efficiency, long life time, strong
directionality of emitted light, low operating voltage, short warm-up
time, and simple operating circuit. Also, GaN-based white LEDs have
durability against external shocks and vibration in order to realize
high-grade light systems having various kinds of packages. Thus,
GaN-based white LEDs may change outdoor light sources to solid-state
lighting such as incandescent lamps, fluorescent lamps, and mercury lamps
in the near future. To utilize GaN-based LEDs as a white light source
that replaces outdoor fluorescent lamps and mercury lamps, the GaN-based
LEDs should emit a high effieiency of output light at a low level of
consumed power and also have excellent thermal stability. Lateral types
GaN-based LEDs that are widely used have a relatively low manufacturing
cost and simple manufacturing process. However, they are not adapted for
use as an outdoor light source because they have a high applied current
and a low light output. A vertical type LEDs may solve the limitations of
the lateral type LED and be easily applied to a high performance LED
having a high light output in a large area. Vertical type LEDs have many
advantages compared to outdoor lateral type devices. Vertical type LEDs
have a low operating voltage and a high light output because they have a
low current diffused resistor and obtain a uniform current spreading.
Vertical type LEDs may have a long life time and a high light output that
are significantly improved because heat is easily transfer to outside
through a metal or semiconductor substrate having superior thermal
conductivity. Vertical type LEDs may be widely used as a white light
source for lighting because they have a maximum applied current of about
three or four times that of lateral type LEDs. Research and development
is being actively carried out on GaN based vertical type LED for
commercialization and improved performance by leading LED companies such
as NICHIA CHEMICAL CO., LTD, JAPAN, PHILIPS LUMILEDS LIGHTING COMPANY,
USA, and OSRAM, GERMANY such as SEOUL SEMICONDUCTOR CO., LTD, SAMSUNG
ELECTRO-MECHANICS CO., LTD, and LG INNOTEK CO., LTD, Korea.

[0004] The light output of a device may be significantly improved by an
n-type semiconductor layer which is placed on the top layer on the device
in the manufacturing of GaN-based vertical type LEDs. In the case where
the semiconductor layer has a smooth surface, total reflection occurs at
the interface between the atmosphere and the semiconductor layer by means
of the refractive index difference between the semiconductor and the
atmosphere (the refractive index of the n-type semiconductor layer is 2.4
or less, and the refractive index of the atmosphere is 1). The device may
not have a highly extracted light output because light is emitted from an
active layer--i.e., the light emitting layer does not emit to the
outside. Thus, minimizing loss from light guiding on semiconductor inside
is required by preventing total reflection by artificially changing the
semiconductor surface. To this end, a nano structure having a pyramid
shape is formed on the n-type semiconductor surface by etching the n-type
semiconductor surface through wet etching using a basic solution such as
KOH, NaOH.

[0005] However, a method that directly forms the pyramid structure on the
n-type semiconductor layer using an existing wet etching process must be
additionally performed in the form of a protective film forming process
to protect the n-type electrode, the conductive substrate, and the mesa
structure of the LEDs. Also, it is difficult to form a uniform nano
structure in a large area.

SUMMARY OF THE INVENTION

[0006] The present invention provides a method of manufacturing a
nanoimprint mold that may be efficiently and economically formed for
enhancing the light extraction efficiency of a light emitting diode, a
method of manufacturing a light emitting diode, and a light emitting
diode using the nanoimprint module.

[0007] Also, the present invention provides a method of manufacturing a
nanoimprinted light emitting diode structure that can efficiently and
precisely form a nano-pattern for enhancing light extraction efficiency
without using an additional wet etching and dry etching process.

[0008] Also, the present invention provides a method of manufacturing a
nanoimprinted light emitting diode system that can efficiently form a
nano-pattern having a large area, thereby reducing costs and simplifying
the process.

[0009] According to an aspect of the present invention, there is provided
a method of manufacturing a nanoimprint mold, the method including:
forming a support substrate supporting a nitride semiconductor substrate
on one surface of the nitride semiconductor substrate; forming a
nano-pattern having a pyramid shape on the other surface of the nitride
semiconductor substrate through wet etching in which the nitride
semiconductor substrate including the support substrate is immersed into
one etchant selected from a calcium hydroxide solution and a sodium
hydroxide solution to irradiate ultraviolet rays onto the nitride
semiconductor substrate; transferring the pyramid-shaped nano-pattern
formed on the other surface of the nitride semiconductor substrate onto
the nanoimprint mold in a commonly nanoimprint method; and separating the
nanoimprint mold, on which the pyramid-shaped nano-pattern is formed,
from the nitride semiconductor substrate.

[0010] The nano-pattern of the nanoimprint mold may be controlled by
adjusting at least one of a molarity of the etchant and a wet etching
time.

[0011] The etchant may have a molarity of about 1 M to about 8 M, and the
wet etching time may range from about 1 minute to about 60 minutes.

[0012] According to another aspect of the present invention, there is
provided a method of manufacturing a light emitting diode, the method
including: forming an n-type nitride semiconductor layer, a light
emitting layer, and a p-type nitride semiconductor layer on a temporary
substrate; forming a p-type electrode on the p-type nitride semiconductor
layer; forming a conductive substrate on the p-type electrode; removing
the temporary substrate to expose the n-type nitride semiconductor layer;
forming a nanoimprint resist layer on the n-type nitride semiconductor
layer; pressing the nanoimprint mold manufactured by the method according
to the present invention on the nanoimprint resist layer to transfer the
pyramid-shaped nano-pattern formed on the nanoimprint mold onto the
nanoimprint resist layer; separating the nanoimprint mold from the
nanoimprint resist layer having the nano-pattern; and etching a portion
of the nanoimprint resist layer having the nano-pattern to form an n-type
electrode.

[0013] The method may further include forming a refractive index
adjustment layer between the n-type nitride semiconductor layer and the
nanoimprint resist layer, and the refractive index adjustment layer may
have a refractive index less than that of the n-type nitride
semiconductor layer and greater than that of the nanoimprint resist
layer.

[0014] The refractive index adjustment layer may be formed by sequentially
stacking a first refractive index adjustment layer and a second
refractive index adjustment layer which refracts light emitted from the
light emitting layer by refractive indexes different from each other.

[0015] The first refractive index adjustment layer may be formed on the
n-type nitride semiconductor layer and have a refractive index less than
that of the n-type nitride semiconductor layer, and the second refractive
index adjustment layer may be formed on the first refractive index
adjustment layer and have a refractive index less than that of the first
refractive index adjustment layer and greater than that of the
nanoimprint resist layer.

[0016] The first refractive index adjustment layer may include at least
one selected from the group consisting of ZnO, Al-doped ZnO, In-doped
ZnO, Ga-doped ZnO, ZrO2, TiO2, SiO2, SiO, Al2O3,
CuOX, and ITO.

[0017] The second refractive index adjustment layer may include MgO-based
oxide.

[0018] The MgO-based oxide forming the second refractive index adjustment
layer may be a multinary-compound formed by adding the other elements in
MgO.

[0019] The n-type electrode may be formed by depositing a conductive
material on an etched area after a portion of the nanoimprint resist
layer having the nano-pattern is etched to expose the n-type nitride
semiconductor layer.

[0020] According to another aspect of the present invention, there is
provided a light emitting diode manufactured according to another aspect
of the present invention.

[0021] According to another aspect of the present invention, there is
provided a method of manufacturing a light emitting diode, the method
including: forming an n-type nitride semiconductor layer, a light
emitting layer, and a p-type nitride semiconductor layer on a substrate
on which a pattern scattering and reflecting incident light is formed;
mesa-etching portions of the p-type nitride semiconductor layer, the
light emitting layer, and the n-type nitride semiconductor layer to
expose a portion of the n-type nitride semiconductor layer; forming a
transparent electrode on the p-type nitride semiconductor layer; forming
the nanoimprint resist layer on the transparent electrode; pressing the
nanoimprint mold manufactured by the method according to the present
invention on the nanoimprint resist layer to transfer the pyramid-shaped
nano-pattern formed on the nanoimprint mold onto the nanoimprint resist
layer; separating the nanoimprint mold from the nanoimprint resist layer
having the nano-pattern; and etching a portion of the nanoimprint resist
layer having the nano-pattern to form a p-type electrode and an n-type
electrode on the n-type nitride semiconductor layer.

[0022] The transparent electrode may include indium tin oxide (ITO).

[0023] The p-type electrode may be formed by depositing a conductive
material on an etched area after a portion of the nanoimprint resist
layer having the nano-pattern is etched to expose the transparent
electrode.

[0024] According to another aspect of the present invention, there is
provided a light emitting diode manufactured according to an aspect of
the present invention.

[0025] According to the present invention, a method of manufacturing a
nanoimprint mold that can be efficiently and economically formed for
enhancing the light extraction efficiency of a light emitting diode, a
method of manufacturing a light emitting diode, and a light emitting
diode using the nanoimprint module are made possible.

[0026] Also, the present invention allows for a method of manufacturing a
nanoimprint module that can efficiently and precisely form a nano-pattern
for enhancing light extraction efficiency without performing additional
wet and dry etching processes.

[0027] Also, the present invention allows for a method of manufacturing a
nanoimprint module that can efficiently form the nano-pattern having a
large area, thereby reducing costs and simplifying the process.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 is a schematic view illustrating light extraction efficiency
decreased by the total internal reflection generated at an interface, due
to different refractive indexes between a nitride semiconductor layer and
the atmosphere, in a related art light emitting diode.

[0029] FIG. 2 is a schematic view illustrating the improvement of the
light extraction efficiency of a light emitting diode according to an
embodiment of the present invention by forming a nano-pattern having a
pyramid shape in a path of light.

[0030] FIGS. 3 to 7 are schematic views illustrating a method of
manufacturing a nanoimprint mold according to an embodiment of the
present invention.

[0031] FIG. 8 is a view illustrating a photograph taken of a nano-pattern
having a pyramid shape formed on a nanoimprint mold by a method of
manufacturing a nanoimprint mold according to an embodiment of the
present invention.

[0032] FIG. 9 is a view illustrating a photograph taken of size changes of
a pyramid nano-pattern of a nanoimprint mold according to the molarity of
an etchant and wet etching time in a method of manufacturing a
nanoimprint mold according to an embodiment of the present invention.

[0033] FIGS. 10 to 18 are views illustrating a method of manufacturing a
light emitting diode according to a first embodiment of the present
invention.

[0034] FIGS. 19 to 25 are views illustrating a method of manufacturing a
light emitting diode according to a second embodiment of the present
invention.

DETAILED DESCRIPTION

[0035] An effect of improving light extraction efficiency according to the
present invention will be described with reference to FIGS. 1 and 2 in
comparison with the related art.

[0036] FIG. 1 is a schematic view illustrating light extraction efficiency
decreased by the total internal reflection generated at an interface, due
to the different refractive indexes between a nitride semiconductor layer
and the atmosphere, in a related art light emitting diode.

[0037] Referring to FIG. 1, in the case where a semiconductor substrate
has a smooth surface, because the refractive index of a gallium nitride
semiconductor substrate is about 2.5 and the refractive index of the
atmosphere is 1, a critical angle with respect to the total reflection is
only 23.5 degrees because of a large refractive index difference between
two layers. Thus, light emitted within a semiconductor is not emitted to
the outside and is dissipated therein to decrease the light extraction
efficiency.

[0038] FIG. 2 is a schematic view illustrating the improvement of the
light extraction efficiency of a light emitting diode according to an
embodiment of the present invention by forming a nano-pattern having a
pyramid shape in a path of light. Referring to FIG. 2, when a
nanostructure having a pyramid shape is formed on a semiconductor
surface, a light extraction efficiency of a light emitting diode may be
substantially improved because the possibility that the light is emitted
to the outside is greatly increased.

[0039] Reference will now be made in detail to the embodiments of the
present invention, examples of which are illustrated in the accompanying
drawings.

[0040] FIGS. 3 to 7 are schematic views illustrating a method of
manufacturing a nanoimprint mold according to an embodiment of the
present invention.

[0041] Referring to FIGS. 3 to 7, a method of manufacturing the
nanoimprint mold according to an embodiment of the present invention
includes a process of forming a support substrate 10 on one surface of a
nitride semiconductor substrate 20, a process of forming a nano-pattern
having a pyramid shape on the other surface of the nitride semiconductor
substrate 20, a process of transferring the nano-pattern having the
pyramid shape to a nanoimprint mold 30 using the nanoimprint method, and
a process of separating the nanoimprint mold 30 having the pyramid-shaped
nano-pattern from the nitride semiconductor substrate 20.

[0042] Referring to FIG. 3, the support substrate 10 is formed on one
surface of the nitride semiconductor substrate 20 for structurally
supporting the nitride semiconductor substrate 20. For example, the
nitride semiconductor substrate 20 used is gallium nitride (GaN).

[0043] Referring to FIG. 4, the nitride semiconductor substrate having the
supporting substrate 10 immersed therein is selected from one etchant
from among an aqueous solution of potassium hydride and an aqueous
solution of sodium hydroxide, and then a pattern having the pyramid shape
is formed on the other surface by a wet etching using an ultraviolet
irradiation.

[0044] In the case where the nitride semiconductor substrate 20 is GaN,
the GaN having a wurtzite crystal structure is an isotropically etched
due to a change in etching rate along a crystal face. Particularly, since
the etching is hardly performed along a (000-1) crystal plane, the
pyramid structure is formed as shown in FIG. 8. A nano-pattern size of
the nanoimprint mold 30 is adjusted to control at least one of etchant
molarity and wet etching time. For example, the molarity of the etchant
may be 1 M or more to 8 M or less, and the wet etching time may be about
one minute to about 60 minutes. FIG. 9 is a comparative picture taken by
an electron microscope of size changes of a nano-pattern according to the
molarity of an etchant and wet etching time. Referring to FIG. 9, the
size of a pyramid nano-pattern formed is easily adjusted to control
etchant molarity and wet etching time.

[0045] Although described hereinafter, the polymer mold for the
nanoimprint--i.e., the nanoimprint mold 30 is formed using the nitride
semiconductor substrate 20 having the pyramid nano-pattern by means of a
master template.

[0046] Referring to FIGS. 5 and 6, the nano-pattern having the pyramid
shape formed on the other surface of the nitride semiconductor substrate
20 transfers the nanoimprint mold 30.

[0047] Referring to FIG. 7, the nanoimprint mold 30 having a
pyramid-shaped nano-pattern is separated from the nitride semiconductor
substrate 20. FIG. 8 is a picture taken by an electron microscope of a
portion of symbol A in FIG. 7.

[0048] Through the process, the nanoimprint mold 30 ultimately having a
pyramid-shaped nano-pattern is formed. The nanoimprint mold 30 is used as
a master template for forming a nano-pattern in a manufacturing process
of a light emitting diode described below.

[0049] FIGS. 10 to 18 are views illustrating a method of manufacturing a
light emitting diode according to a first embodiment of the present
invention.

[0050] Referring to FIGS. 10 to 18, a method of manufacturing a light
emitting diode according to a first embodiment of the present invention
includes a process of forming an n-type nitride semiconductor layer 110,
a light-emitting layer 120, and a p-type nitride semiconductor layer 130
on a temporary substrate 100, a process of forming a p-type electrode 140
on the p-type nitride semiconductor layer 130, a process of forming a
conductive substrate 150 on the p-type electrode 140, a process of
exposing the n-type nitride semiconductor layer 110 by removing the
n-type nitride semiconductor layer 110, a process of forming a
nanoimprint resist layer 160 on the n-type nitride semiconductor layer
110, a process for transferring a nano-pattern transferred onto the
nanoimprint resist layer 160 by pressing a nanoimprint mold 30 that is
formed by the method of manufacturing a nanoimprint mold according to the
present invention on the nanoimprint resist layer 160, a process of
separating the nanoimprint mold 30 from the nanoimprint resist layer 160
having the nano-pattern, and a process of forming an n-type electrode 170
by etching a portion of the nanoimprint resist layer 160 having the
nano-pattern.

[0052] Referring to FIG. 11, the p-type electrode 140 is formed on the
p-type nitride semiconductor layer 130, and the conductive substrate 150
is formed in the p-type electrode 140.

[0053] The p-type electrode 140 also performs a function that reflects
light from the light-emitting layer 120.

[0054] Referring to FIG. 12, the n-type nitride semiconductor layer 110 is
exposed to the outside by removing the temporary substrate 100.

[0055] Referring to FIG. 13, the nanoimprint resist layer 160 is formed on
the n-type nitride semiconductor layer 110 by the method of spin coating,
for example.

[0056] Referring to FIGS. 14 and 15, a nano-pattern is transferred onto
the nanoimprint resist layer 160 by pressing the nanoimprint mold 30 that
is formed by the method of manufacturing the nanoimprint module according
to the present invention as described above on the nanoimprint resist
layer 160.

[0057] Referring to FIG. 16, the nanoimprint mold 30 is separated from the
nanoimprint resist layer 160 having a pyramid-shaped nano-pattern, and
then the nanoimprint resist layer 160 is heated by UV rays and heat to
cure the nanoimprint resist layer 160 having a pyramid-shaped
nano-pattern.

[0058] Referring to FIG. 17, a portion of the nanoimprint resist layer 160
having a pyramid-shaped nano-pattern is etched for exposing the n-type
nitride semiconductor layer 110, and then the n-type electrode 170 is
formed. For example, the n-type electrode 170 etches a portion of the
nanoimprint resist layer 160 having a pyramid-shaped nano-pattern to
expose the n-type nitride semiconductor layer 110, and may then be formed
on an etched region by removing a conductive material.

[0059] Also, the first embodiment of the present invention may include a
process of additionally forming a refractive index adjustment layer 180
for enhancing the light extraction efficiency.

[0060] That is, referring to FIG. 18, the refractive index adjustment
layer 180 is formed having a lower refractive index than the refractive
index of the n-type nitride semiconductor layer 110 and higher than the
refractive index of the nanoimprint resist layer 160 between the n-type
nitride semiconductor layer 110 and nanoimprint resist layer 160 before
forming the nanoimprint resist layer 160.

[0061] The refractive index adjustment layer 180 is sequentially formed by
stacking the first refractive index adjustment layer 181 and the second
refractive index adjustment layer 182 which reflect emitted light from
the light-emitting layer 120 and having the same refractive index.

[0062] The first refractive index adjustment layer 181 is formed on the
n-type nitride semiconductor layer 110 such that the refractive index of
the first refractive index adjustment layer 181 is lower than the
refractive index of the n-type nitride semiconductor layer 110, the
second refractive index adjustment layer 182 is formed on the first
refractive index adjustment layer 181 such that the refractive index of
the second refractive index adjustment layer 182 is lower than the
refractive index of the first refractive index adjustment layer 181 and
is higher than the refractive index of the nanoimprint resist layer 160.
The first refractive index adjustment layer 181 and the second refractive
index adjustment layer 182 have an intermediate refractive index between
those of the n-type nitride semiconductor layer 110 and the nanoimprint
resist layer 160 to perform the function of a buffer layer, thereby
further enhancing light extraction efficiency.

[0063] For example, the first refractive index adjustment layer 181 may
include at least one selected from the group consisting of ZnO, Al-doped
ZnO, In-doped ZnO, Ga-doped ZnO, ZrO2, TiO2, SiO2, SiO,
Al2O3, CuOX, and ITO, and the second refractive index
adjustment layer 182 may include MgO-based oxide. The MgO-based oxide
forming the second refractive index adjustment layer 182 may be a
multinary compound formed by adding the other elements in MgO. All of the
materials have a refractive index between the refractive index of the
n-type nitride semiconductor layer 110 and the refractive index of the
nanoimprint resist layer 160 selected from the first refractive index
adjustment layer 181 and the second refractive index adjustment layer
182.

[0064] As described in detail above, the present invention allows for a
method of manufacturing a nanoimprint mold that can be efficiently and
economically formed for enhancing the light extraction efficiency of a
light emitting diode, a method of manufacturing a light emitting diode,
and a light emitting diode using the nanoimprint module.

[0065] Also, the present invention allows for a method of manufacturing a
nanoimprint module that can efficiently and precisely form a nano-pattern
for enhancing light extraction efficiency without using an additional wet
etching and dry etching process.

[0066] Also, the present invention allows for a method of manufacturing a
nanoimprint module that can efficiently form a nano-pattern having a
large area, thereby reducing costs and simplifying the process.

[0067] In more detail, the technique of the present invention, as a
process for forming a pyramid nanostructure using a method of
nanoimprinting a large area, may be immediately applicable to a
manufacturing process of the light emitting diode. Moreover, the
technique of the present invention may be applicable to a vertical or
lateral type light emitting diode. According to the technique of the
present invention, a manufacturing process may become simpler, and the
light output of a light emitting diode may be drastically improved. The
present invention relates to an energy saving eco friendly technique that
welcomes a solid-state lighting age using white light GaN-based LEDs.

[0068] As described above, although the preferred embodiments of the
present invention are described with reference to the accompanying
drawings, the present invention is not limited to specific embodiments.
Also, it will be understood by those skilled in the art that various
changes and imitation in form and details may be made therein without
departing from the spirit and scope of the invention as defined by the
appended claims.

[0069] FIGS. 19 to 25 are views illustrating a method of manufacturing a
light emitting diode according to a second embodiment of the present
invention.

[0070] Referring to FIGS. 19 to 25, a method of manufacturing a light
emitting diode according to a second embodiment includes a process of
forming an n-type nitride semiconductor layer 210, a light-emitting layer
220, and a p-type nitride semiconductor layer 230 on a semiconductor
substrate 200 having a pattern for reflecting light through scattering, a
process of exposing a portion of the n-type nitride semiconductor layer
210 by mesa-etching a portion of the p-type nitride semiconductor layer
230, the light-emitting layer 220, and the p-type nitride semiconductor
layer 230, a process of forming a transparent electrode layer 240 on the
p-type nitride semiconductor layer 230, a process of forming a
nanoimprint resist layer 250 on the transparent electrode layer 240, a
process of transferring a nano-pattern transferred onto a nanoimprint
resist layer 250 by pressing the nanoimprint resist layer 250 that is
formed by the method of manufacturing a nanoimprint module according to
the present invention on the nanoimprint resist layer 250, a process of
separating the nanoimprint mold 30 from the nanoimprint resist layer 250
having the nano-pattern, and a process of forming a p-type electrode 260
by etching a portion of the nanoimprint resist layer 250 having the
nano-pattern and forming an n-type electrode 270 on the n-type nitride
semiconductor layer 210.

[0071] Referring to FIG. 19, the n-type nitride semiconductor layer 210,
the light-emitting layer 220, and the p-type nitride semiconductor layer
230 are sequentially formed on a substrate 200 having a nano-pattern for
reflecting incident light. The substrate 200 may be a substrate formed of
sapphire (Al2O3), and the nano-pattern formed on the substrate
200 performs a function for reflecting emitting light through scattering
from the light-emitting layer 220.

[0072] Referring to FIG. 20, a portion of the n-type nitride semiconductor
layer 210 is exposed by mesa-etching a portion of the p-type nitride
semiconductor layer 230, the light-emitting layer 220, and the n-type
nitride semiconductor layer 210.

[0073] Referring to FIG. 21, the transparent electrode layer 240 is formed
on the p-type nitride semiconductor layer 230 etched by the mesa-etching,
and the nanoimprint resist layer 250 is formed on the transparent
electrode layer 240 through a method of spin coating, for example. The
transparent electrode layer 240 may include Indium Tin Oxide (ITO).
Referring to FIGS. 23 and 23, a nano-pattern is transferred onto the
nanoimprint resist layer 250 by pressing the nanoimprint mold 30 that is
formed by the method of manufacturing the nanoimprint module according to
the present invention as described above on the nanoimprint resist layer
250.

[0074] Referring to FIG. 24, the nanoimprint mold 30 is separated from the
nanoimprint resist layer 250 having a pyramid-shaped nano-pattern, and
then the nanoimprint resist layer 250 is heated by UV rays and heat to
cure the nanoimprint resist layer 250 having a pyramid-shaped
nano-pattern.

[0075] Referring to FIG. 25, a portion of the nanoimprint resist layer 250
having a pyramid-shaped nano-pattern is etched for exposing the n-type
nitride semiconductor layer 210, and then, the p-type electrode 260 is
formed on the portion of the p-type electrode 260, and the n-type
electrode 270 is formed on the n-type nitride semiconductor layer 210.
For example, the n-type electrode 270 etches a portion of the nanoimprint
resist layer 250 having a pyramid-shaped nano-pattern to expose the
transparent electrode layer 240, and may then be formed on an etched
region by removing a conductive material, and the n-type electrode 270 is
formed on the n-type nitride semiconductor layer 210 remained after the
mesa-etching.